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Target volume definition in radiation therapy.

Target volume definition in radiation therapy is a broad field of interdisciplinary research. We give a brief history of clinical research in this field and outline some remarkable steps which led to the well-defined target volume concepts. The challenges in target volume definition for high-precision conformal radiation therapy are discussed, and possibilities of improving target volume definition, such as the integration of modern imaging modalities and the use of computer-based systems to support the radiation oncologist are indicated, as well as novel techniques for increasing the accuracy of patient positioning. All these tools should be evaluated with regard to their potential for increasing the therapeutic ratio and, as appropriate, should be implemented in clinical practice. However, target volume definition is a complex process influenced by many factors, currently under investigation. While questions remain in this field, and the impact of the influencing factors is not defined, the process of target volume definition should remain the subject of clinical research.

Humans↗

Epidermal growth factor receptor antagonists: novel therapy for the treatment of high-grade gliomas.

Overactivation of epidermal growth factor receptor (EGFR) signaling has been recognized as an important step in the pathogenesis and progression of multiple forms of cancer of epithelial origin. This knowledge has led to a surge of interest in novel anticancer therapies targeting key constituents of the EGFR signal transduction pathway. Several molecular strategies have been developed recently to modulate either EGFR or the downstream signal beyond the cell surface receptor. The important role of aberrant EGFR signaling in the progression of malignant gliomas makes EGFR-targeted therapies of particular interest in this form of cancer. The use of anti-EGFR therapies against malignant brain tumors, although in its infancy, promises to yield exciting results as these new drugs probably will enhance the usefulness of existing therapies.

Brain Neoplasms↗

The potential for gene-targeted radiation therapy of cancers.

Targeted cancer therapy is the mantra now chanted by oncologists of all types. Everyone hopes that the rapid expansion in the knowledge of cancer cell genetics, signaling, regulatory factors and other changes that underlie malignant transformation and metastasis will lead to innovative approaches for the treatment of cancers. To date, successful targeted therapies have been derived from pharmaceutical chemistry - designing chemical compounds intended to disrupt a crucial pathway for malignant cells to survive, grow and metastasize. Radiotherapy also has a goal of more-selective targeting of therapeutic radiation effects to only tumor cells. In this review, we describe our efforts to create a form of gene-targeted radiation therapy by using the unique radiation effects of radionuclides that decay by the Auger process attached to oligonucleotide carrier-molecules that are capable of forming triplex DNA structures with target sequences in the genome of the human cancer cell.

Combined Modality Therapy↗

Identification of tumor vascular antigens by monoclonal antibodies prepared from rat-tumor-derived endothelial cells.

We have reported the isolation and specific in vitro properties of tumor-derived endothelial cells (TEC) from rat KMT-17 fibrosarcomas transplanted into rats. To develop antibody-based tumor vascular targeting therapy for solid tumors, we have generated monoclonal antibodies (MAbs) using passive immunization of outside-out membrane vesicles of rat epididymal-fat-pad-derived capillary endothelial cells (FCEC) followed by active immunization of those of rat TEC. The MAbs produced were screened against TEC and FCEC. Of all cultured hybridomas, 75 (3.3%) of the secreted MAbs preferentially recognized TEC. We selected a total of 7 MAbs which detected antigens highly abundant in TEC, although 5 of the 7 MAbs were weakly positive for FCEC in cell-ELISA and FACS analyses. The antigens recognized by these MAbs, with the exception of MAb TES-7, were present on endothelial cells of tumor blood vessels in KMT-17 fibrosarcoma tissues, as shown by immunohistochemical analysis. Antigens of 40- and 80-kDa were recognized by MAbs TES-1, 7, 17, 21 and 26 and by MAbs TES-23 and 27 respectively. Although the function of these antigens, which are preferentially expressed on rat tumor-derived endothelial cells, is still unknown, we believe that future studies of such antigens will help elucidate the role of endothelial cells in tumor vasculature. Our results indicate that MAbs may provide a novel tool for the development of antibody-based therapy targeting tumor vasculature.

Animals↗

Relevance of pathologic classifications and diagnosis of acute myeloid leukemia to clinical trials and clinical practice.

Many new insights into the diagnosis, pathogenesis, clinical manifestation, treatment and prognosis of patients with AML reflect the heterogeneity of the disease. The initial descriptions of the various subtypes of AML, established by the FAB classification, were based on morphology and cytochemical stains. Although morphology remains the foundation for the diagnosis, additional diagnostic studies including immunophenotyping, cytogenetic evaluation, and molecular genetic studies have become critical, and in some specific cases, mandatory, complementary tools. Several specific subtypes of AML are now treated with directed or targeted therapy. Acute promyelocytic leukemia is currently the only example of a subtype of AML to which specific therapy targeted to a molecular genetic abnormality is available and this subtype now is highly curable. Future studies will address newly identified prognostic factors and gene mutations such as FLT3, Wilm's tumor (WTI), and CEBPA which will enable the further pathologic classification of patients with AML. Finally, microarray analysis will likely identify genes critically involved in the pathogenesis of specific pathologic subtypes.

Acute Disease↗

A pilot study of the liposomal MUC1 vaccine BLP25 in prostate specific antigen failures after radical prostatectomy.

PURPOSE: Men with biochemical failure after radical prostatectomy have few therapeutic options other than androgen deprivation therapy. Targeted therapies in this group are appropriate because the optimal timing of the initiation of hormonal therapy in this patient population is unknown. A single institution pilot trial was performed using BLP25 liposome vaccine in hormone naïve patients with prostate specific antigen failure after radical prostatectomy to determine if prostate specific antigen progression could be halted. MATERIALS AND METHODS: Men with biochemical failure after radical prostatectomy were enrolled. Primary end points were efficacy and safety of the MUC1 BLP25 liposomal vaccine. Changes in prostate specific antigen doubling time were also evaluated. Patients received a single intravenous dose of cyclophosphamide, followed by vaccinations with BLP25 liposome vaccine for up to 1 year. Prostate specific antigen was measured at baseline and during treatment, and prostate specific antigen doubling time was calculated for these intervals. RESULTS: A total of 16 patients with a median age of 60 years were enrolled. All patients received cyclophosphamide and 15 of 16 completed the primary treatment period. Ten patients completed the maintenance period. After the 8-week primary treatment period 8 of 16 patients had stable or decreased prostate specific antigen. At the last on-study prostate specific antigen measurement 1 patient maintained stable prostate specific antigen but all others had progression. However, 6 of the 16 patients had greater than 50% prolongation of prostate specific antigen doubling time compared to pre-study prostate specific antigen doubling time. CONCLUSIONS: BLP25 liposome vaccine shows promise for prolonging prostate specific antigen doubling time in hormone naïve men with biochemical failure after prostatectomy and little morbidity. This could potentially translate into the deferral of hormonal therapy. Further testing in this population of patients is warranted.

Aged↗

Recent developments in inflammatory bowel disease.

The evolving medical armamentarium holds promise for more precise and effective therapies for IBD. The experience with anti-TNF therapy, particularly infliximab, illustrates the potential efficacy of therapies targeted at specific mediators or pathways involved in the pathogenesis. Advances in molecular technology have enabled the development of novel and potentially effective targeted therapies. Equally important is the increasing scientific understanding of the pathogenesis of IBD, which will likely improve the ability to stratify disease and to select therapies based on genotypic, immunologic, and phenotypic profiles in the future.

Adjuvants, Immunologic↗

Dermatofibrosarcoma protuberans: a surgical disease with a molecular savior.

PURPOSE OF REVIEW: Dermatofibrosarcoma protuberans is a low-grade malignancy of the skin and subcutaneous tissues with low potential for the development of distant metastases. This tumor is characterized by infiltrative growth, and a chromosomal translocation involving the COL1A1 gene on chromosome 17 and the gene platelet-derived growth factor B gene on chromosome 22. This review will examine recent data confirming the central role of surgery in managing this disease and new findings for the application of molecularly targeted therapy in patients with unresectable disease. RECENT FINDINGS: The largest published series of dermatofibrosarcoma protuberans cases has reported that surgery can lead to excellent local control in dermatofibrosarcoma protuberans in over 95% of cases. In patients with metastatic disease, or with locally advanced disease not suitable for surgical excision, inhibition of platelet-derived growth factor receptors with imatinib (Gleevec) can lead to striking clinical results, including complete responses in some patients. SUMMARY: The identification of platelet-derived growth factor B as a near universal translocation partner in chromosomal rearrangements in dermatofibrosarcoma protuberans has led to the successful application of therapy targeted at platelet-derived growth factor receptors. Although wide surgical excision remains the standard of care, patients with locally advanced disease not suitable for wide surgical excision or with metastatic disease can be managed with the platelet-derived growth factor receptors inhibitor imatinib with high probability of response.

Adult↗

Diverse gene expression and DNA methylation profiles correlate with differential adaptation of breast cancer cells to the antiestrogens tamoxifen and fulvestrant.

The development of targeted therapies for antiestrogen-resistant breast cancer requires a detailed understanding of its molecular characteristics. To further elucidate the molecular events underlying acquired resistance to the antiestrogens tamoxifen and fulvestrant, we established drug-resistant sublines from a single colony of hormone-dependent breast cancer MCF7 cells. These model systems allowed us to examine the cellular and molecular changes induced by antiestrogens in the context of a uniform clonal background. Global changes in both basal and estrogen-induced gene expression profiles were determined in hormone-sensitive and hormonal-resistant sublines using Affymetrix Human Genome U133 Plus 2.0 Arrays. Changes in DNA methylation were assessed by differential methylation hybridization, a high-throughput promoter CpG island microarray analysis. By comparative studies, we found distinct gene expression and promoter DNA methylation profiles associated with acquired resistance to fulvestrant versus tamoxifen. Fulvestrant resistance was characterized by pronounced up-regulation of multiple growth-stimulatory pathways, resulting in estrogen receptor alpha (ERalpha)-independent, autocrine-regulated proliferation. Conversely, acquired resistance to tamoxifen correlated with maintenance of the ERalpha-positive phenotype, although receptor-mediated gene regulation was altered. Activation of growth-promoting genes, due to promoter hypomethylation, was more frequently observed in antiestrogen-resistant cells compared with gene inactivation by promoter hypermethylation, revealing an unexpected insight into the molecular changes associated with endocrine resistance. In summary, this study provides an in-depth understanding of the molecular changes specific to acquired resistance to clinically important antiestrogens. Such knowledge of resistance-associated mechanisms could allow for identification of therapy targets and strategies for resensitization to these well-established antihormonal agents.

Breast Neoplasms↗

EZH2 Suppression Diversifies Prostate Cancer Lineage Variant Evolution and Lacks Efficacy in Inhibiting Disease Progression.

UNLABELLED: Advanced prostate cancer remains a leading cause of cancer-related death among men due to disease progression in nearly all patients on standard-of-care therapy targeting the androgen receptor. An important mechanism driving therapeutic resistance is lineage plasticity, which enables prostate cancer cells to reprogram into lineage variants no longer dependent on androgen receptor signaling. As inhibitors of the histone methyltransferase enhancer of zeste homolog 2 (EZH2) are being evaluated clinically for the treatment of advanced prostate cancer, we investigated in this study how EZH2 affects prostate cancer lineage plasticity. Data from genetically engineered mice and human clinical samples demonstrated that genetic or pharmacologic suppression of EZH2 altered chromatin to expand active transcription factor programs. These changes in gene expression during prostate cancer progression increased the diversity of prostate cancer lineage variants that arose. EZH2 suppression did not inhibit disease progression nor therapeutic resistance in this context. These findings advance the current understanding of prostate cancer lineage plasticity and suggest that EZH2 inhibitors may be less effective in treating prostate cancer prone to lineage plasticity. SIGNIFICANCE: EZH2 suppression diversifies prostate cancer lineage plasticity, which has implications for EZH2-targeted therapies that are being evaluated for prostate cancer treatment. See related commentary by Thienger et al., p. 827.

Enhancer of Zeste Homolog 2 Protein↗

[Children with cancer--great progress, a lot of good news and some disappointments].

Each year, between 125 and 150 children under the age of 15 develop cancer in Norway. More than half of the children are less than five years of age at diagnosis. The malignancy is often of an embryonal origin and the disease spectrum very different from that in adults. Our progress in understanding and treating childhood malignancies is one of the success stories in paediatrics and in cancer biology and management. In the Nordic countries, about three of four children with cancer are cured, but the progress is different in different disease groups. For some malignancies, survival is close to 100%, while progress for other types have been much slower. However, cancer is still the main cause of death in children above one year of age who die of a disease. The progress has its price. The treatment is often intensive, with great morbidity and a definite mortality. Late effects are also of great concern. A more specific therapy targeted against the malignant cell, with less damage to normal cells, has long been our goal. Progress in recent years in the understanding of the malignant cells has now given the first definite examples that such targeted therapy may soon become a reality.

Adolescent↗

[Ertapenem and other antibacterials].

Ertapenem is a carbapenem that shares the activity of imipenem and meropenem against most species, but is less active against non-fermenters. The activity is retained against most strains with AmpC and extended-spectrum beta-lactamases, although the resistance can arise if these enzymes are combined with extreme impermeability. The resistance can also be caused by IMP, VIM, KPC and NMC carbapenemases, but again, co-requires impermeability. Although the spread of carbapenemases in the future is a concern, they are currently very rare. Given as a 1 g intravenous (i.v.) infusion once daily, ertapenem has a plasma half-life of -4 h in healthy volunteers, and a Cn,a, of 155 mg/l and 13 mg/l for total and free drug, respectively. Excretion is largely renal, divided equally between native drug and an open-ring derivative. The trials showed equivalence to piperacillin/tazobactam or ceftriaxone in (a) abdominal infections, (b) community-acquired pneumonia, (c) acute pelvic infections, (d) skin and skin structure infections and (e) complicated urinary tract infections. The USA licence grants all these five indications; the ED licence grants the first three. Further potential uses include home i.v. therapy, target therapy against Enterobacteriaceae with AmpC or extended-spectrum cephalosporinases, and tentatively, surgical prophylaxis. Widening the usage of carbapenems raises public health concerns, somewhat allayed by the continued rarity of carbapenemases after 17 years of imipenem use, and by the fact that carbapenemases occur mostly in non-fermenters outside the spectrum of ertapenem, and co-require impermeability to confer resistance in Enterobacteriaceae. Nevertheless, if ertapenem is to be used widely, its effects on the microbial resistance ecology need to be monitored carefully.

Anti-Bacterial Agents↗

Congenital atresia of the external ear and tinnitus: a new syndrome.

Congenital atresia of the external ears and severe tinnitus has been reported by two patients to be contralateral to the atretic ear. The use of the nuclear medicine imaging technique of single-photon emission computed tomography (SPECT) of brain has demonstrated hypoperfusion in brain areas supplied by the middle cerebral artery on the side of the atretic ear. Ultrahigh-frequency audiometry (UHFA) has revealed a bilateral loss of hearing greater than expected for the age of affected patients. Quantitative electroencephalography (QEEG) has shown a significant central nervous system electrical dysfunction correlated with the SPECT of brain findings. One case is reported in detail at this time. Completion of the medical audiological tinnitus patient protocol, including SPECT of brain, UHFA, and QEEG, accurately established the clinical tinnitus diagnosis of predominantly a central-type tinnitus, a clinical hypothesis that the medical significance of the tinnitus is a "soft" sign of cerebrovascular disease, and provided a rationale for treatment directed to a presumed ischemia of brain based on a receptor-targeted therapy targeted to the GABA-A receptor, resulting in significant tinnitus relief. Questions that have arisen include (1) the incidence of occurrence of hypoperfusion of the middle cerebral artery in congenital atresia patients; (2) implications and long-term consequences of this finding in this patient population for development of cerebrovascular disease; (3) brain plasticity for tinnitus relief (i.e., neuronal reprogramming, particularly in response to treatment recommendations for complaints of the cochleovestibular system in general and specifically for tinnitus); (4) the clinical significance of the UHFA thresholds of bilateral hearing loss greater than expected for the age of the patient; and (5) whether congenital atresia of the external ear may be part of a syndrome that includes hypoperfusion in brain areas supplied by the middle cerebral artery on the side of the atretic ear, ultra-high-frequency bilateral loss of hearing greater than expected for the age of the patient, and significant central nervous system electrical dysfunction. As far as we can determine, these findings, highlighted by the brain SPECT, have not previously been reported in patients with congenital atresia of the external ear.

Adult↗

Efficacy of epidermal growth factor receptor-targeted molecular therapy in anaplastic thyroid cancer cell lines.

Anaplastic thyroid cancer is one of the most aggressive human malignancies and the outcomes of conventional therapy have been far from satisfactory. Recently, epidermal growth factor receptor (EGFR)-targeted therapy has been introduced as an alternative therapeutic strategy for highly malignant cancers. This study was undertaken to investigate the expression of EGFR in anaplastic thyroid cancer cell lines, and to explore the potential of therapies targeting EGFR as a new therapeutic approach. EGFR was universally expressed in anaplastic cancer cell lines at a variety of levels. Specific EGFR stimulation with epidermal growth factor showed significant phosphorylation of ERK1/2 and Akt, and resulted in marked growth stimulation in an anaplastic thyroid cancer cell line, which highly expressed EGFR. This EGFR-transmitted proliferation effect of the cancer cell line was completely inhibited by gefitinib, an EGFR tyrosine kinase inhibitor. Moreover, growth of xenografts inoculated in mice was inhibited in a dose-dependent manner with 25-50 mg kg(-1) of gefitinib administrated orally. Inhibition of EGFR-transmitted growth stimulation by gefitinib was clearly observed in anaplastic thyroid cancer cell lines. Our results suggested that EGFR-targeted therapy, such as gefitinib, might be worth further investigation for the treatment of anaplastic thyroid cancer.

Animals↗

Pathogenesis-oriented targets for adjunctive therapy.

The outcome of patients with sepsis arises from multiple factors affecting both the host and the invading microorganisms. Even within the setting of adequate antimicrobial use, patients still die of sepsis. Thus, strategies focusing on further therapy targets are an important area of interest for basic and clinical research. Although such adjunctive sepsis therapy has failed to achieve consistent better survival rates so far, the progress in understanding of the pathophysiology of sepsis seen in recent years is so profound, that the possibility that a new and effective treatment may arise should be warmly considered. Indeed, it may be considered that efficacious interventions, such as early and vigorous fluid replacement, strict blood glucose control, low-dose corticosteroid reposition, protective mechanical ventilation and activated-protein C are pathogenic-oriented targets of therapy. In this paper we aim to review some aspects of the pathogenesis of sepsis, focusing on possible targets for adjunctive therapy. Published clinical trials and experimental data supporting such trials are commented on.

Animals↗

Tumor-associated antigens as possible targets for immune therapy in head and neck cancer: comparative mRNA expression analysis of RAGE and GAGE genes.

Specific immune therapy targeting residual areas of cancer cells may emerge as a powerful treatment strategy for head and neck squamous cell carcinoma (HNSCC). In order to define possible targets for immune therapy, we evaluated the frequency of two groups of tumor antigens-the RAGE and GAGE families-by means of reverse transcriptase polymerase chain reaction using primary HNSCCs (n = 28), mucosa specimens as normal controls (n = 10) and HNSCC cell lines (n = 6). By means of specific primer selection we could differentiate between RAGE-1, -2, -3 and -4, as well as between two groups of GAGE genes (GAGE-1,2,7 vs GAGE-3,4,5,6,8). While all mucosa tissues (from smokers and non-smokers) were negative for both antigen families, 24/28 investigated tumors were positive for up to 5 tumor antigens. Among the RAGE genes, RAGE-1-positive tumors were the most abundant (8/28), followed by RAGE-2 (7/28) and RAGE-4 (6/28). Differences in the locations of HNSCCs were reflected by different RAGE family members being expressed most frequently: larynx, RAGE-1; oropharynx, RAGE-2; and hypopharynx, RAGE-4. Primers against GAGE-1,2,7 and GAGE-3,4,5,6,8 revealed 6/27 and 16/27 positive tumors, respectively. This report suggests that RAGE genes and GAGE-3,4,5,6,8 may be promising candidates for specific immune therapy in HNSCC.

Antigens, Neoplasm↗

Pathogenetic aspects of sepsis and possible targets for adjunctive therapy.

The outcome of patients with sepsis arises from multiple factors affecting both the host and the invading microorganisms. Age, presence of underlying disease, source of infection and some specific etiological agents have been related to prognosis. Appropriateness of antimicrobial therapy, considering the in vitro susceptibility tests for the infecting bacteria, has been strongly associated with the outcome. Therefore even after the cascade of sepsis has been triggered, the control of bacteria growth is still fundamental for the outcome of the infection. This is a major distinction point from experimental studies in which whole killed bacteria and their products are used as model of sepsis. However, even within the setting of adequate antimicrobial use, patients still die of sepsis. Thus, strategies focusing on further therapy targets are an important area of interest for basic and clinical research. Although such adjunctive sepsis therapy has failed to achieve consistent better survival rates so far, nevertheless, it improved our understanding of the pathophysiological events seen in sepsis that the possibility that a new and effective treatment may arise has been warmly considered. In this paper we aim to review some aspects of the pathogenesis of sepsis, focusing on recent advances and on possible targets for adjunctive therapy. Published clinical trials and experimental data supporting such trials are commented on.

Animals↗